The present invention relates to a vehicle headlamp which is constructed to emit light so as to form a low beam light-distribution pattern, and more particularly to a so-called projector-type vehicle headlamp.
In general, in projector-type vehicle headlamps, a projection lens is disposed on an optical axis which extends in a longitudinal direction of a vehicle and a light source is disposed rearward of a rear-side focal point of the projection lens, whereby light from the light source is reflected towards the optical axis by a reflector.
Then, JP-U-02-047704 and JP-A-2001-229715 describe the projector-type vehicle headlamps adopting a sideways insertion-type headlamp construction in which the light source is made up of a light emitting portion of a light source bulb which is inserted from a side of the optical axis into the reflector so as to be fixed thereto.
As this occurs, in the vehicle headlamp described in JP-A-2001-229715, a shade for covering part of reflected light from the reflector is provided in the vicinity of the rear-side focal point of the projection lens to thereby emit light so as to form a low beam light-distribution pattern.
The longitudinal length of a lamp can be shortened so that the lamp is attempted to be made compact in size, in case the sideways insertion-type lamp construction described in JP-U-02-047704 and JP-A-2001-229715.
However, in the vehicle headlamps described in JP-U-02-047704 and JP-A-2001-229715, since the light source bulb is inserted and fixed to the reflector on the same horizontal plane as the optical axis, there is caused the following problem.
Namely, in the projector-type vehicle headlamps, while an optical axis sideways area on a reflecting surface of the reflector is suitable for formation of a diffused area of the low beam light-distribution pattern, in the event that the light source bulb is inserted and fixed to the reflector on the same horizontal plane as the optical axis, since an inserting and fixing hole of the light source bulb has to be formed in the optical axis sideways area on the reflecting surface, the optical axis sideways area cannot be used effectively to control the light distribution, and this causes a problem that it becomes difficult to ensure a sufficient brightness at the diffused area of the low beam light-distribution pattern.